1. Technical Field
Exemplary embodiments of the present invention relate to a semiconductor device, and more particularly, to a phase-change random access memory device and a method of manufacturing the same.
2. Related Art
Phase-change random access memory (PCRAM) devices have a simple structure, realize high integration with a low cost, and perform high speed operation.
As well known, the PCRAM devices are a current driving type of memory device in which data is stored by changing a crystalline state of a phase-change material layer by a heating electrode, that is, a heater.
In the PCRAM devices, control of a set current for transition of the phase-change material layer to a crystalline state and control of a reset current for transition of the phase-change material layer to an amorphous state serve as essential factors for determining performance of the PCRAM devices.
In particular, a bottom electrode contact which is the heating electrode has been changed in various types to reduce the reset current. An example thereof will be described with reference to FIG. 1.
FIG. 1 is a cross-sectional view illustrating a structure of a conventional PCRAM device, which is taken along a bit line direction of the PCRAM device.
Referring to FIG. 1, a switching device 12 is formed on a semiconductor substrate 10 and a bottom electrode contact 14 electrically connected to the switching device 12 is formed on the switching device 12. A phase-change material layer 16 is formed on the bottom electrode contact 14.
In particular, the bottom electrode contact 14 may be formed in a line type to minimize a contact area with the phase-change material layer thereon.
In FIG. 1, for example, the phase-change material layer 16 is described as a partially confined structure. Thus, the phase-change material layer 16 having the partially confined structure allows a thermal effect between adjacent cells to be minimized.
However, the existing PCRAM device is fabricated without separation between the phase-change material layers 16 in the bit line direction as shown in FIG. 1. Therefore, when a distance between the adjacent cells is not significantly ensured, a distance between phase transition regions 18 is reduced in a cell operation. Therefore, the cells of the PCRAM may be vulnerable to disturbance therebetween. With high integration of the cells, the distance between the adjacent cells becomes more reduced so that the cells may malfunction due to the disturbance therebetween.